Electron discharge device

ABSTRACT

7. A high-power electron discharge rectifier, comprising an anode and a cathode supported in spaced relation thereto, said anode comprising a substantially cylindrical member of plurallayer material defining a barrel portion generally enclosing said cathode and a pair of free ends, said plural-layer material comprising at least one layer of high heat conductivity material disposed to form the surface of the barrel nearer said cathode, whereby to facilitate conductive cooling of said anode and thus to minimize formation of hot spots thereon, and means joining said ends in juxtaposed relation over a portion thereof to define a web, the remote end portions being outwardly flared to provide oppositely extending wings.

United States Patent Millis ELECTRON DISCHARGE DEVICE Inventor: Walter T. Millis, Owensboro, N.Y.

Assignee:

Filed:

Appl. No.:

General Electric Company Oct. 2, 1958 References Cited UNlTED STATES PATENTS 11/1963 Ochsner et a1. ..29/l83.5

Feb. 13, 1973 EXEMPLARY CLAIM 7. A high-power electron discharge rectifier, comprising an anode and a cathode supported in spaced relation thereto, said anode comprising a substantially cylindrical member of plural-layer material defining a barrel portion generally enclosing said cathode and a pair of free ends, said plural-layer material comprising at least one layer of high heat conductivity material disposed to form the surface of the barrel nearer said cathode, whereby to facilitate conductive cooling of said anode and thus to minimize formation of hot spots thereon, and means joining said ends in juxtaposed relation over a portion thereof to define a web, the remote end portions being outwardly flared to provide oppositely extending wings.

17 Claims, 5 Drawing Figures .Pmmwrmmw 3,716,736

INVENTORZ WALTER T. MILLIS,

BYjOQaeu/Q HIS TOR EY.

ELECTRON DISCHARGE DEVICE This invention relates to electron discharge devices, and more particularly to electrode constructions for such devices.

Miniaturization of electron discharge devices and increasingly larger demands for electrical power performance of such devices have correspondingly increased the requirements established for temperature tolerance and heat-handling capacity of anodes employed therein.

Also, as a result of current demands for tube reliability, elimination of anode hot spots or localized heating of anodes must be attained to avoid undesired evolution of gas from anodes as well as any undesired local heating of the cathode, grid and tube envelope.

I-Ieretofore, to reduce anode temperature, it has been proposed to use, for anodes, such materials as carbonized nickel and aluminum-clad iron because of the heat-radiating properties of such materials.

However, the efficacy of such radiating materials is effectively limited by the anode shape and size which, of course, are determined largely by other considerations. For example, I have observed that because of the relatively low thermal conduction properties of nickel or iron, any attempt to augment this by a mere increase in radiation area is ultimately productive of a point at which further increases in area results in such increase in heat resistance as to offset any expected increase in radiation. Similarly, merely to increase the thickness of the materials commonly used results in such undue increase in mass as to render such expedients uneconomical.

It is, therefore, an object of this invention to avoid the above noted defects of anodes heretofore proposed for use in electron discharge devices.

It is another object of my inventionto increase the heat dissipating action of such anodes without altering the size or shape thereof.

Another object of my invention is to provide improved electron discharge devices having anode electrodes in which good heat-radiating and conducting elements are cooperatively related, whereby maximum heat dissipation is obtained for minimum efiective radiation cross section.

In the accomplishment of the foregoing objectives, l provide novel electron-discharge tube devices comprising anode constructions formed of composite strip material of threeor five-layer composition wherein a strip of high-heat conductivity material such as copper is provided with a cladding of aluminum-clad steel on one face only to form the three-layer composition, or, on both faces to form the five-layer composition. Anodes constructed of either form are characterized in that both thermal radiation and conduction properties are excellent so that the generation of localized hot spots in the anode is minimized and uniform heating of the anode is enhanced. Furthermore, evolution of gases from the anode is reduced by virtue of the overall reduction of the temperature of the anode, thereby substantially increasing the operating life of the tube.

As will appear, anodes constructed of the three-layer strip material possess certain added advantages when utilized in tubes of the diode or rectifier type, while anodes constructed of the five-layer material possess certain additional advantages when employed in amplifier tubes having grid electrodes disposed between the cathode and anode.

For a better understanding of my invention reference may be had to the accompanying drawing in which:

FIG. 1 is an elevational view of an electron discharge device incorporating an anode according to one form of my invention;

FIG. 2 is a cross sectional view taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged view of a part of the anode construction of the device of FIGS. 1 and 2;

FIG. 4 is an elevational view of an electron discharge device incorporating an anode according to another form of the invention; and

FIG. 5 is an enlarged fragmentary view of the anode construction embodied in the device of FIG. 4.

I have shown, in FIGS. 1 and 2, an electron discharge device 11 of the rectifier type comprising an envelope 12 within which an anode construction of this invention is incorporated. The device may include a conventional or indirectly heated cathode 13 that is heated by a filamentary heater 15, or if desired, the cathode may be of the directly heated type in which case the sleeve 13 may be omitted. An anode electrode 17, in accordance with the invention, is formed of a three-layer strip material which, as shown more clearly in FIG. 3, comprises a base layer 19 of copper on one face of which is suitably bonded an intermediate layer of iron 21, which, in turn, carries a cladding of aluminum 23.

While the individual layers 19, 21 and 23 may be bonded together in any suitable manner, it is preferable that they be processed to form a metallurgical bond. Material found to be satisfactorily bonded is available from the Metals and Control Corporation, Attleboro, Massachusetts, under its code designation C26D. Inasmuch as the process of fabricating the composite material, in and of itself, is not my invention, a fuller description of the process is not deemed to be necessary.

In forming the anodic material for use in the rectifier of FIG. 1, it will be observed that a cylindrical barrel portion 25 is provided of which the copper layer 19 is innermost, the aluminum layer 23 forming the exterior wall portion thereof. The free ends of the strip material are placed in vis-a-vis position to define a web 27 and locked or secured together by any suitable means such as stakes 29, beyond which the extending portions of the free ends are outwardly flared to define oppositely extending wings 30, the remote radiating surfaces of which, it will be noted are constituted of the copper layer 19.

The anode and cathode assembly is supported within the envelope as by micas 31 (FIG. 1) and connection to external circuitry is effected by the usual leads 32 for the anode and 33 for the cathode, which, as shown, passes through the envelope to a conventional top cap seal 35.

For clarity of illustration, the connection of the cathode 13 to the lead 33 is shown in FIG. 2 as comprising a flexible conductive connection 37 spotwelded at one end to the cathode l3 and, at the other, to one leg 39 of a double-legged support structure for a getter and getter shield assembly, as shown at 41 (FIG. 1 The getter may be of the ring-shaped type compris ing an annular frame 43 containing any suitable gettering material, the frame resting on and secured to a getter flash shield 45 in the form of a flat circular metallic disc supported by diametrally disposed metallic legs 39 which, in turn, are supported on the top mica 31. Lead 33 is conductively connected to the shield 45 as by spot welding, and thus, by means of the legs 39 and connection 37, to the cathode l3.

ln operation of the rectifier device hereinabove described, the advantages flowing from the novel anode construction will be apparent when considered in the light of the extremely high thermal concentration on the anode normally experienced with anodes of conventional construction. The copper layer of the anode facilitates distribution of the heat from the relatively narrow anode portion on which the electrons from the cathode directly impinge, minimizing the formation of localized hot spots. The redistribution of the heat contributes to a reduction in the overall temperature of the anode thus reducing markedly the liberation of gases from the anode and adds operating life for the tube.

It will be observed further that the presentation of a copper surface to the cathode is compatible with improved cathode emission, it having been observed that copper has effectively no cathode-poisoning effect.

The thermal efficiency of the cathode is also markedly improved by the use of my anode construction; one operative embodiment showing an increase in cathode temperature of substantially 100C for a cathode-power input equal to that of a conventional rectifier with a nickel anode surface facing the cathode.

ln rectifiers of closely spaced cathode and anode electrodes, the application of the herein described copper-iron aluminum anode construction permits the use of an enlarged cathode diameter or emissive area for the same heater power, thus permitting increased cathode-to-anode spacing, which, it will be appreciated, retains the perveance of the device unchanged.

Still another advantage of the presently described invention resides in the fact that the reduction in anode temperature in those portions next adjacent the cathode reduces undesired back emission from the anode, while the highly-reflective smooth copper surface minimizes points of high-voltage field intensity, thus reducing substantially the problem of arc over.

FIGS. 4 and 5 illustrate an amplifier type electron discharge device in which an anode of the five-layer strip mate rial is embodied. As shown, the amplifier may comprise an envelope 50 which may be evacuated and enclose the usual indirectly heated cathode 52 and grid 54 electrodes supported in coaxially disposed relation between a pair of mica spacers 56. Supported in coaxial relation in the cathode and grid is an anode electrode 58 according to this invention, which, as shown more clearly in FIG. 5, preferably comprises a five-ply orlayer material having a central core 60 of copper on each side of which is suitably bonded layers 62, 64 of iron, on which are clad layers of aluminum 66, 68. The

7 layers of aluminum-clad iron may be bonded on the opposite surfaces of the copper core in any suitable manner, it being preferable that the processing be such as to form metallurgical bonds, as above noted, in connection with the three-ply material. Suitable material of the five-ply type just described is obtainable from the Metals and Controls Corporation above mentioned under the code number A51 material.

The device of FIGS. 4 and 5 may be provided with the usual getter assembly generally shown at 70 and electrode leads as at 72 for the usual functions performed thereby.

ltwill be observed that the anode 58 is formed with an aluminum layer on each of the outer surfaces of the strip. Thus, the aluminum, upon being heated, reacts with the under layer of iron to produce at the outermost surfaces, a darkened surface of FeAl having excellent heat-radiating and absorption properties.

By presenting such a darkened anode surface in close proximity to the grid 54, the absorption of the heat from the grid reduces markedly the grid temperature which effectively reduces grid emission. The darkened outer surface enhances radiation from the anode and the anode-enclosed components.

In all other respects the anode 58 just described has been found to provide advantages similar to those described above in connection with the three-ply anode 17 of FIGS. l-3.

In determining the relative amounts of copper, iron, and aluminum for the three-ply and five-ply strip materials, it will be appreciated that as much copper should be provided as is possible for heat conduction, while sufficient iron should be provided for desired structural strength.

In successfully operating embodiments, I have found that the three-ply material, as above described, as used in diode rectifiers, may desirably be formed in overall thickness of 0.005 inch, 0.007 inch, and 0.010 inch, and the five-ply material, as above described, as used in grid-controlled amplifiers, may desirably be formed in overall thickness of the same dimensions.

The following table shows the ranges of copper thicknesses which have been found to provide satisfactorily operating materials of the type described for each of the indicated overall thickness of the three and fiveply materials.

Note a: The upper limit is established by requirements of particular applications under consideration, and as determined by the fact that the iron thickness should be no less than 0.002 inch.

Note b: The upper limit is established by the minimum thickness of iron practicable for structural strength which for most applications should be no iess than 0.002 inch on each side of the copper core.

From the above table it will be seen that the average percentage of copper, in terms of the overall thickness of material, is approximately 40 percent with the desirable thickness of copper ranging from a minimum of the order of 10 percent to a maximum of the order of percent. In both types of material, I have found that aluminum thickness of approximately 0.0005 inch provides satisfactory blackening due to the formation of F6Ai What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electron discharge device comprising an anode and a cathode supported in spaced relation therefrom, said anode having a substantially pure copper surface in next adjacent relation to said cathode and an overlay of aluminum-clad iron remote from said cathode the thickness of the copper relative to that of the anode ranging from about 8 percent to about 75 percent.

2. An electron discharge device comprising cathode, grid and anode electrodes supported in mutually spaced relation, said grid electrode being interposed between said cathode and anode electrodes, said anode electrode comprising a five-layer strip material including a core portion of copper and outer portions of aluminum-clad iron.

3. An electron discharge device comprising an anode in the form of a strip material of predetermined thickness and having a plurality of metallic layers at least one of which is copper of which the thickness is not less than approximately 10 percent of the overall thickness of said strip material, thereby to ensure desired heat conductivity characteristics in said anode.

4. An anode for electron discharge devices comprising a composite multiple-layer strip material having at least three layers of dissimilar materials one of which is copper, the thickness of the copper layer being approximately 40 percent that of the composite material, thereby to ensure desired structural strength characteristics in said anode, two others of said layers being of materials adapted to yield, at the temperature of operation of said anode, a reaction product having high heatradiating properties.

5. A high-power electron discharge rectifier, comprising an anode and a cathode supported in spaced relation thereto, said anode comprising asubstantially cylindrical member of plural-layer material defining a barrel portion and a pair of free ends, said plural-layer material comprising at least one layer of high heat conductivity metal disposed to form the innermost surface of the said barrel, means joining said ends in juxtaposed relation over a portion thereof to define a web, the remaining end portions being outwardly flared to provide oppositely extending wings.

6. The rectifier as defined in claim 5, wherein said high heat conductivity metal is copper.

7. A high-power electron discharge rectifier, comprising an anode and a cathode supported in spaced relation thereto, said anode comprising a substantially cylindrical member of plural-layer material-defining a barrel portion generally enclosing said cathode and a pair of free ends, said plural-layer material comprising at least one layer of high heat conductivity material disposed to form the surface of the barrel nearer said cathode, whereby to facilitate conductive cooling of said anode and thus to minimize formation of hot spots thereon, and means joining said ends in juxtaposed relation over a portionthereof to define a web, the remote end portions being outwardly flared to provide oppositely extending wings.

8. The rectifier as defined in claim 7, whereinsaid wings have heat-radiating surfaces comprised of said high heat conductivity metal.

9. An electron discharge device comprising a cylindrical electrode formed as a multi-layer element having at least three discrete layers of dissimilar metals metallurgically bonded to each other, the inner layer being of copper, the thickness of the copper layer relative to that of the electrode ranging from about 10 percent to about 75 percent to provide a predetermined heat conductivity characteristic for said electrode, two other layers being of materials adapted, in response to heating of said electrode, to provide a reaction product having high heat-radiating properties.

10. An electron discharge device comprising a hollow anode formed as a multi-layer element having at least three layers of dissimilar metals bonded together to form an integral element, the inner layer being of copper, the thickness of the copper layer relative to that of the anode ranging from about 8 percent to about 64 percent to provide a predetermined heat conductivity characteristic for said electrode and simultaneously to ensure desired structural strength for said anode, two other contiguous layers being of material adapted, in response to heating of said anode, to provide a reaction product having high heat-radiating properties.

11. An anode for electron discharge devices comprising a composite multiplelayer strip material having at least three layers of dissimilar materials in juxtaposed relation, an outer one of which layers is of copper, the thickness of the copper layer being approximately 40 percent of that of the composite material, thereby to ensure desired thermal conductivity and structural strength characteristics in said anode, two other layers being of iron and aluminum, respectively, of which a portion is in the form of FeAl 12. An anode for electron discharge devices comprising a composite multi-layer strip material comprising five layers in juxtaposed relation, the inner-most of said layers being of copper, the thickness of the copper layer being approximately 40 percent that of the composite material, two other layers being of iron and aluminum, arranged in pairs, one on each side of said copper layer, portions at least of said iron-aluminum pairs being in the form of FeAl 13. An electron discharge device comprising an anode formed of a five-layered composite material, said material in cross section comprising two layers of aluminum each metallurgically bonded to a respective one of two layers of steel and said layers of steel metallurgically bonded to and sandwiching therebetween a layer of copper, said copper layer having a thickness comprising less than 40 percent of the thickness of said five-layered composite material, and said composite material being approximately 0.005 of an inch in thickness.

14. An electron discharge device comprising an anode formed of a five-layered composite material, said material in cross section comprising two layers of aluminum each metallurgically bonded to a respective one of two layers of steel and said layers of steel metallurgically bonded to and sandwiching therebetween a layer of copper, said copper layer having a thickness comprising less than 40 percent and at least 16 percent of the thickness of said five-layered composite material, and said composite material being approximately 0.005 of an inch in thickness.

15. Composite anode material comprising a plurality of metallurgically bonded metallic layers at least five of which layers comprise aluminum, iron, copper, iron and aluminum, in that order; said composite anode material being approximately 0.005 of an inch in thickness, and said copper layer having a thickness comprising less than 40 percent and at least 16 percent of the thickness of said composite anode material.

cally bonded to and sandwiching therebetween a layer of copper, said copper layer having a thickness comprising less than 40 percent and at least 16 percent of the thickness of said five-layered composite material, and said composite material being approximately 0.005 of an inch in thickness.

UNHEB ST TES PATENT @IFHQE QERTEFEQA'EE @i RRE$EN Patent No. 3, 716, 736 Dated February 13, 1973 Inventor(s) Walter P. MilliS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claims l3, l4, l5, l6, and 17 are cancelled.

Signed and sealed this 10th day of July 1973 (SEAL Attest:

EDWARD M. PLETCHER,JR. n Tegtmeyer Attesting Officer Acting Commissioner of Patents F ORM PO-1 050 (10-69) USCOMM-DC scam-Pas] 1? US. GOVERNMENT wwu-nur n -ICE- man fi-'4GR- 

1. An electron discharge device comprising an anode and a cathode supported in spaced relation therefrom, said anode having a substantially pure copper surface in next adjacent relation to said cathode and an overlay of aluminum-clad iron remote from said cathode the thickness of the copper relative to that of the anode ranging from about 8 percent to about 75 percent.
 2. An electron discharge device comprising cathode, grid and anode electrodes supported in mutually spaced relation, said grid electrode being interposed between said cathode and anode electrodes, said anode electrode comprising a five-layer strip material including a core portion of copper and outer portions of aluminum-clad iron.
 3. An electron discharge device comprising an anode in the form of a strip material of predetermined thickness and having a plurality of metallic layers at least one of which is copper of which the thickness is not less than approximately 10 percent of the overall thickness of said strip material, thereby to ensure desired heat conductivity characteristics in said anode.
 4. An anode for electron discharge devices comprising a composite multiple-layer strip material having at least Three layers of dissimilar materials one of which is copper, the thickness of the copper layer being approximately 40 percent that of the composite material, thereby to ensure desired structural strength characteristics in said anode, two others of said layers being of materials adapted to yield, at the temperature of operation of said anode, a reaction product having high heat-radiating properties.
 5. A high-power electron discharge rectifier, comprising an anode and a cathode supported in spaced relation thereto, said anode comprising a substantially cylindrical member of plural-layer material defining a barrel portion and a pair of free ends, said plural-layer material comprising at least one layer of high heat conductivity metal disposed to form the innermost surface of the said barrel, means joining said ends in juxtaposed relation over a portion thereof to define a web, the remaining end portions being outwardly flared to provide oppositely extending wings.
 6. The rectifier as defined in claim 5, wherein said high heat conductivity metal is copper.
 7. A high-power electron discharge rectifier, comprising an anode and a cathode supported in spaced relation thereto, said anode comprising a substantially cylindrical member of plural-layer material defining a barrel portion generally enclosing said cathode and a pair of free ends, said plural-layer material comprising at least one layer of high heat conductivity material disposed to form the surface of the barrel nearer said cathode, whereby to facilitate conductive cooling of said anode and thus to minimize formation of hot spots thereon, and means joining said ends in juxtaposed relation over a portion thereof to define a web, the remote end portions being outwardly flared to provide oppositely extending wings. 7.A HIGH-POWER ELECTRON RECTIFIER, COMPRISING AN ANODE AND A CATHODE SUPPORTED IN SPACED RELATION THERETO, SAID ANODE COMPRISING A SUBSTANTIALLY CYLINDRICAL MEMBER OF PLURAL-LAYER MATERIAL DEFINING A BARREL PORTION GENERALLY ENCLOSING SAID CATHODE AND A PAIR OF FREE ENDS, SAID PLURAL-LAYER MATERIAL COMPRISING AT LEAST ONE LAYER OF HIGH HEAT CONDUCTIVITY MATERIAL DISPOSED TO FORM THE SURFACE OF THE BARREL NEARER
 8. The rectifier as defined in claim 7, wherein said wings have heat-radiating surfaces comprised of said high heat conductivity metal.
 9. An electron discharge device comprising a cylindrical electrode formed as a multi-layer element having at least three discrete layers of dissimilar metals metallurgically bonded to each other, the inner layer being of copper, the thickness of the copper layer relative to that of the electrode ranging from about 10 percent to about 75 percent to provide a predetermined heat conductivity characteristic for said electrode, two other layers being of materials adapted, in response to heating of said electrode, to provide a reaction product having high heat-radiating properties.
 10. An electron discharge device comprising a hollow anode formed as a multi-layer element having at least three layers of dissimilar metals bonded together to form an integral element, the inner layer being of copper, the thickness of the copper layer relative to that of the anode ranging from about 8 percent to about 64 percent to provide a predetermined heat conductivity characteristic for said electrode and simultaneously to ensure desired structural strength for said anode, two other contiguous layers being of material adapted, in response to heating of said anode, to provide a reaction product having high heat-radiating properties.
 11. An anode for electron discharge devices comprising a composite multiple-layer strip material having at least three layers of dissimilar materials in juxtaposed relation, an outer one of which layers is of copper, the thickness of the copper layer being approximately 40 percent of that of the composite material, thereby to ensure desired thermal conductivity and structural strength characteristics in said anode, two other layers being of iron and aluminum, respectively, of which a portion is in the form of FeAl3.
 12. An anode for electron discharge devices comprising a composite multi-layer strip material comprising five layers in juxtaposed relation, the inner-most of said layers being of copper, the thickness of the copper layer being approximately 40 percent that of the composite Material, two other layers being of iron and aluminum, arranged in pairs, one on each side of said copper layer, portions at least of said iron-aluminum pairs being in the form of FeAl3.
 13. An electron discharge device comprising an anode formed of a five-layered composite material, said material in cross section comprising two layers of aluminum each metallurgically bonded to a respective one of two layers of steel and said layers of steel metallurgically bonded to and sandwiching therebetween a layer of copper, said copper layer having a thickness comprising less than 40 percent of the thickness of said five-layered composite material, and said composite material being approximately 0.005 of an inch in thickness.
 14. An electron discharge device comprising an anode formed of a five-layered composite material, said material in cross section comprising two layers of aluminum each metallurgically bonded to a respective one of two layers of steel and said layers of steel metallurgically bonded to and sandwiching therebetween a layer of copper, said copper layer having a thickness comprising less than 40 percent and at least 16 percent of the thickness of said five-layered composite material, and said composite material being approximately 0.005 of an inch in thickness.
 15. Composite anode material comprising a plurality of metallurgically bonded metallic layers at least five of which layers comprise aluminum, iron, copper, iron and aluminum, in that order; said composite anode material being approximately 0.005 of an inch in thickness, and said copper layer having a thickness comprising less than 40 percent and at least 16 percent of the thickness of said composite anode material.
 16. The electron discharge device as set forth in claim 15 and wherein each of said aluminum layers are exposed outer layers. 